1. Field of the Invention
The invention relates to flame retardants for use in flexible polyurethane foam composition and a method of flame retarding flexible polyurethane foam. Specifically, the invention relates to a composition comprising flammable flexible polyurethane foam and a multi-component flame retardant additive.
2. Description of Related Art
The flexible polyurethane foams of the invention are well known in the [chemical] industry. Information on preparation and common reactants can be found in many resources, including the ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING, Vol. 13 (John Wiley & Sons, Inc., 1988).
Flexible polyurethane foam producers desire to produce foam that meets flammability standards with higher fire safety requirements when used in furniture applications. California has proposed increasing the flammability criteria in the form of Bulletin 117. The U.S. Congress and Consumer Product Safety Commission are moving toward a national fire safety standard for upholstered furniture.
Flame retardants based upon pentabromodiphenyl oxide (PBDE) and alkylated triaryl phosphates have traditionally been used to meet the fire safety requirements. Recently pentabromodiphenyl oxide has come under attack owning to concerns about its impact on the environment. Consequently “PBDE free” flame retardants have been used in greater volumes and have been promoted as more environmentally sound alternatives.
U.S. Pat. No. 4,746,682 discloses a liquid composition for use as a flame retardant additive for polyurethane foams, the process of preparing the flame retarded polyurethane foam and the foam itself. The liquid composition is an additive for a polyurethane foam comprising polybrominated diphenyl oxide and an alkylated triaryl phosphate ester, the brominated diphenyl oxide and triaryl phosphate being provided in sufficient quantity to provide between 0.7 and 4 parts by weight bromine per part by weight of triaryl phosphate.
U.S. Pat. No. 5,728,760 discloses a method of making flame retarded polyurethanes by including a bromobenzoate compound in a polyurethane mixture and a method of making flame retarded polyvinyl chlorides, unsaturated polyesters and epoxy resins by incorporating a bromobenzoate compound into the polymer system. The bromobenzoate compounds may also be used as plasticizers for PVC and rubber. “PBDE free” flame retardants as described in U.S. Pat. No. 5,728,760, known as Firemaster 550, a product of Great Lakes Chemical Corporation, now known as Chemtura Corporation, is a blend of a tetrabromobenzoate and an isopropylated triaryl phosphate. However, Firemaster 550 typically has to be used at levels approximately 5% higher than the PBDE based flame retardants in low density foams (1.2 pound per cubic foot (p.c.f.)). This increase in flame retardant load level increases the cost to produce the resulting polyurethane foam.
The industry lacks a flame retardant system that meets the more stringent flammability requirements and has similar or improved efficiency as compared to the traditional PBDE based flame retardants.